G2/M arrest of MDA-MB-468 caused by eupatorin is due in part to metabolism to cirsiliol and can be reversed by acacetin. (a) Cell cycle analysis of MDA-MB-468 cells co-treated with 10 μM eupatorin and 1.5 μM acacetin for 48 hours. Histograms are one trace of three independent experiments. (b) Cell cycle profile of MDA-MB-468 cells treated with 10 μM cirsiliol for 48 hours. The experiment was performed in duplicate.